You say "organize". Is your home what you'd call disorganized?
If it's 'only you' in the home, do you mean rather that you don't feel inspired to do the basics of cleaning/tidying up?
I can understand that, if you feel that no one will see it anyway. It does feel, even to me sometimes, that I'm the only one who notices the work I've put into cleaning!
I often wonder what my own home would be like if I had no one living here but myself.
I would think that if dishes needed doing, I'd do them.
Beds made, a quick vac, dust when necessary etc...
If a thorough cleaning each week is important to you, then just start, as one person said, one room at a time, more if you have the energy.
Sorry but other than that, if you live on your own, I can't even imagine it looking disorganized unless you haven't done a tidy up/purge of unused items/ fridge/freezer clean in ages, as necessary.
Just do what you can do, tidy rather than clean, and enjoy your free time doing something you would like to do!